Proposed work will continue our investigation of the physiology of GIP secretion by completing the studies on the role of the autonomic nervous system on glucose stimulated GIP secretion. In addition, we will determine which factors, insulin secretory reserve, duration of diabetes, obesity or the presence of pancreatic glucagon are associated with excessive GIP response to mixed meals observed in diabetes and whether the excessive GIP response to mixed meals can be restored to normal by normalizing postprandial glycemia using an artificial endocrine pancreas (BIOSTATOR-GCIIS). Six subjects in each of the following groups will be studied during and after taking a standard mixed meal, once while receiving conventional insulin therapy and again when the glucose is controlled by the BIOSTATOR: insulin dependent diabetics, lean insulin independent diabetics, obese insulin independent diabetics, totally pancreatectomized diabetics and new onset insulin requiring diabetics.